Rail Pressure Troubleshooting

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Starting to have a dead pedal symptom. When I shift, sometimes the pedal goes dead, no engine response for a second or 2, then it comes back to life. Initially it started as a hiccup. Would just be noticeable between shifts. No codes, new symptom is first start today was rough, low idle, ran ~5 seconds then died. Started back up with no issues, minus the hiccup/dead pedal issues. Around a year ago had the FCA go out. Replaced it ran fine.

This winter I have had to plug the block heater in since the batteries are going out. Or else they almost don't have enough juice to start the truck after cycling the grid heater. Yea I have one bad grid heater solenoid so only running on one heater now as well.

Another thing that I finally tied into voltage is once it gets cold enough for the grid heaters, is that when the grid heater cycles off, and battery voltage comes back up the dash dings and some warning lights flash.

I have the smarty touch and desired charging voltage is 15V. Is that a little high? Trying to figure out how to display the datalog I took with the smarty to see when the non-responsive pedal is tied to something else.

The 2 red top optimas I'm running are maybe 8-9 years old. They were in my 01 ram. Got this truck and swapped them over. Wondering if bad batteries could cause this. If so, I have to research batteries now.

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Well the problem did evolve into an fca. Except now I would be putting in my third fca. Gotta be something else.

Problem started as a hiccup during shifting. Got worse to where it is undrivable. Swapped in a new ca. Truck ran till I switched fuel filters. Won't maintain fuel rail pressure. Sometimes after startup rail pressure hangs around 21k. When it hits idle, trying to take off pressure drops to around 1500. It will normally catch and not stall. Swapped in another fca. Ran fine then later after the testdrive, went to go back out. Truck doing the same thing. I really doubt I got 2 bad fca in a row. Only running a smarty touch with egt.

Edited January 31, 2016 by 2500ctd

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Good batteries and the charging system are essential. From my experience issues with one will ultimately cause issues with the other if not promptly dealt with. 15volts sounds a little high. Most alternators regulate around 14.5 maximum output.

Regarding your rail pressure... still no codes?? how is your lift pump pressure? The ECM controls the FCA by reading various sensor inputs. Bad info in means bad info out.

Typically idle should be around 6k PSI. I would say there is something wrong if 21k PSI just after starting. For the rail to drop out so much trying to move I wonder if the lift pump isn't capable of keeping up?

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You guys ask all the questions I have and cant answer. I don't have a lift pump gauge on it yet. However I did order the parts for a test gauge setup along with the miller tools to test the return rates. Its an in-tank lift pump. Hoping I don't have to pull the module but thinking I should anyways since the truck is down. My initially thoughts about why the first FCA was a bad batch of fuel, as about a month ago the water in fuel light on. Never had that happen before. I did recently change where I filled up as well. As soon as the special fitting come in Ill get to testing the return rates. I hope I find something wrong.

There is a 4 part video on youtube about testing the hpcr system. Anyone know of any other tests? Nothing in the factory FSM. I might have to get the diesel supplement.

Edited January 31, 2016 by 2500ctd

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When bought my BD lift pump I also purchased a Vulcan big line kit with a pressure T to replace the line going from the OEM filter canister to the CP3. The lines, high flow fittings, and T with the pressure port was only $30 some bucks.... just makes it easy to add a gauge later.

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Bob, just some suggestions for reliability which may not solve your problem.

Get rid of the inside the tank lift pump and go with a Fass with the filters. Cut out the screens inside the tank and get the 1/2'' drawstraw so your not picking up fuel thru the factory drawstraw which has a very small screened cartridge on it..

Get rid of all banjo bolts by going with 1/2'' fuel lines.

Get rid of the factory APPS and get the Timbo Apps.

Sometimes I think the guys around here miss these thinks just to make have to post.

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Not sure on how to test that. I have a smarty touch. Rail pressure seem to mimic the truck. At max pressure truck sounds like crap. Same as unplugging the fca. When it would almost die, rail pressure went down to under 4K with the worse it bouncing around 1700-2000 psi.

It did take a bit longer to build rail pressure. Longer then normal. I gotta have something returning to much fuel.

I am suspecting all this is due to a tank or 2 of bad fuel. I recently switch stations. (Cheapest in town, Arco)shortly after, around a week filling up the water in fuel light came on. Never happened to me before. Not in the 01 nor the 05 till then. Pulled over, drained it and good to go. Well about a month later the dead pedal starts. Initially it started as a hiccup during shifting. At first I thought it was me. So slight. Well now…

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I am suspecting all this is due to a tank or 2 of bad fuel. I recently switch stations. (Cheapest in town, Arco)shortly after, around a week filling up the water in fuel light came on. Never happened to me before. Not in the 01 nor the 05 till then. Pulled over, drained it and good to go. Well about a month later the dead pedal starts. Initially it started as a hiccup during shifting. At first I thought it was me. So slight. Well now…

I had the same thing happen years ago. Local ma and pop station got fuel didn't make it much farther than 5 miles and the WIF light came on. After doing some study work and how the local fuel station tended their pumps and delivery of fuel. So now I know like the Chevron I get fuel at has high quality water blocking filter at the pumps. Now as for the Mom and pop is just a standard paper filter that passes water no good.

More or less get what you pay for you want cheap dirty watered down fuel or spend a few pennies more a gallon for quality fuels.

Edited February 11, 2016 by Mopar1973Man

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Just finished testing the hprv. Passed, no fuel from it. Setup to do the injector return test. According to the video, truck needs to be at operating temp. Not going to do that with max rail pressure, so I have it plugged in now.

I did pull the fca and do the shake test lol I know that test is pointless I actually pulled it to see if there was anything I can see that might have gotten in there and maybe jammed the fca yea I'm reaching. Of course no change.

Must has no trouble hitting 26kpsi. Seems slow to build pressure though. With it at idle and max rail pressure, the initial lift pump pressure was @ 7psi. A quick throttle tap. Dropped to 5 but no lower. Figure at max rail pressure and 5 psi. Intank pump is at least good enough to rule out for this issue which I didn't think it was the lift pump but the psi test is easy enough.

Banjo bolts look like a little rust on them or is it just me?

What about mounting aux filters higher then the tank? They will be higher then the tank but lower then the engine mounted filter. During filter changes, I will probably crack a line to let the fuel drain down to minimize spillage. Plus they are up and hidden. Ill post pics when installed. I don't believe it to be an issue as the pump still has to lift the fuel up to the stock filter level, and being the intank pump, its all pushing fuel. Much gooder for the pump as opposed to drawing fuel up that high.

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Hmmm, Fuel looks like crap.. Regardless the ECM should not be allowing your rail pressure to climb that high. If your FCA is good ? It seems to me the ECM may not be getting a good reference, and thinks the rail pressure is actually low. The RPS should have a voltage that fluctuates from 0-.5 volts as the pressure changes .5 volts is equal to 0 psi .

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Well the problem did evolve into an fca. Except now I would be putting in my third fca. Gotta be something else.

Problem started as a hiccup during shifting. Got worse to where it is undrivable. Swapped in a new ca. Truck ran till I switched fuel filters. Won't maintain fuel rail pressure. Sometimes after startup rail pressure hangs around 21k. When it hits idle, trying to take off pressure drops to around 1500. It will normally catch and not stall. Swapped in another fca. Ran fine then later after the testdrive, went to go back out. Truck doing the same thing. I really doubt I got 2 bad fca in a row. Only running a smarty touch with egt.

If the rail pressure is that high at idle you don't have a HPRV issue, which you have tested, and I am going to guess you have a bad FCA or Rail Pressure sensor. Really those are the only two things that will cause high rail pressure at idle.

Program the truck stock and see if any codes pop up. The Smarty tuning may disable a code or two that could help with troubleshoot... but then again maybe now.

How long does the truck sit between running? I have found that the Touch will drain the batteries in 2-3 weeks and have to unplug mine when it sits more than a few days.

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just over the weekend. During the winter cold starts, when it isn't plugged in almost doesn't crank fast enough. Plugged in for about 3 hrs before I leave and starts easier. Batteries are old. I don't think they'll last another winter.

I will keep that in mind about the smarty. Ill return it to stock and then keep it unplugged till I needed.

That would be the 3rd FCA. Not saying it cant be, just I don't buy it. Also with the cloudy fuel I could have other issues. The pressure appears to be working. Truck sounds/behavior mimic the RP on the smarty. I will see if I can test the sensor. should be a 5V sensor. Nothing to difficult......famous last words.

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When the issues started I swapped the FCA which was within a year of my last one. Under warranty. When I picked that one up I got a new fuel filter. Swapped FCA's. Ran fine. Swapped the filter and then it ran like crap. Got another FCA ran fine till the next morning. I have no codes, Havent checked recently just after the new FCA went out. No codes. Ill program the truck back to stock and scan for codes.

Smarty is showing rail pressure desired at 6000 at idle, and the actual is 26112. Good thing I guess is during the HPRV test there was no leakage. Bone dry. At least that isn't leaking.

No one to swap FCAs with. After swapping out the 2nd one, I drove the truck down to return it. Next morning, max rail pressure.

It is slow to build rail pressure cranking but after it starts it maxes.

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